Synergistic induction of blood-brain barrier properties

Abstract

Blood-brain barrier (BBB) models derived from human stem cells are powerful tools to improve our understanding of human cerebrovascular diseases and facilitate drug development for the brain. Yet providing endothelial cells with the appropriate molecular cues to both retain a vascular identity and acquire BBB characteristics remains challenging. Here we present cARLA, an easy-to-use and affordable small molecule cocktail that robustly induces BBB properties in vitro. By activating cyclic AMP and Wnt/β-catenin signaling while inhibiting the transforming growth factor beta (TGF-β) pathway, cARLA synergistically enhances barrier tightness in a range of BBB models. We demonstrate that, upon cARLA treatment, human stem cell-derived endothelial cells have lower rates of transcytosis, higher glycocalyx density and increased efflux pump activity with a shift in gene expressional profile towards the in vivo brain endothelial signature. Our work provides mechanistic insight into how endothelial signaling is orchestrated during BBB maturation and leverages this to advance the prediction of drug delivery to the human brain.

Lab-on-a-chip models of the blood–brain barrier: evolution, problems, perspectives

“…The first BBB-on-chip model, a lab-on-a-chip (LOC) device incorporating brain endothelial cells was described 12 years ago 2 (Fig. 1), [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] and since then more than 150 papers have been published on microfluidic chip devices and the BBB. Importantly, all these models are based on cultured cells of the BBB.…”

“…1). [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Culture models are widely used and valuable tools in basic and preclinical research to study the cellular and molecular aspects of BBB physiology, pharmacology and pathology. 17,18 Following the first observation that endothelial cells grow out from isolated rat cerebral capillaries in sterile culture conditions 7 many advancements have been made in this field (Fig.…”

“…1). [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] One of the major milestones was the introduction of culture inserts containing porous membranes to grow primary brain endothelial monolayers. 8 This was the first BBB model with two fluid compartments, mimicking the vascular and brain sides, to allow permeability assays and later the measurement of transendothelial electrical resistance (TEER).…”

“…15 Finally, to enhance the weak barrier and other BBB characteristics of iPSC-derived human models differentiated from endothelial progenitors, a new method was invented simultaneously targeting multiple signaling pathways using small molecules. 16 The long-term goal is to create human body-on-chip systems with integrated BBB-onchips for biomedical research including disease modeling, drug discovery and personalized medicine. 19 In this review we present the main types of BBB-on-chip models and their use for the investigation of certain aspects of BBB physiology, drug and nanoparticle transport, toxicology and selected areas of pathology.…”

“…[2][3][4][5][6] References for the selected major milestones of BBB culture models in order of publication time. [7][8][9][10][11][12][13][14][15][16] differences between cerebral and peripheral endothelial cells on many levels, only BBB-on-chip devices with brain endothelial cells are discussed. Our main goals are to identify knowledge gaps, neglected engineering and cell biological aspects, to point out problems and contradictions in the literature of BBB-on-chip models, and to suggest areas for further studies to progress this highly interdisciplinary field.…”